HR: 08:15h
AN: H51G-02 INVITED     [Abstracts]
TI: The Fine Structure of Water-Quality Dynamics: the Wave of the Future in Catchment Hydrochemistry?
AU: * Kirchner, J W
EM: kirchner@seismo.berkeley.edu
AF: Department of Earth and Planetary Science, University of California, Berkeley, CA 94720-4767 United States
AU: Feng, X
EM: xiahong.feng@dartmouth.edu
AF: Dept. of Earth Sciences, Dartmouth College, Hanover, NH 03755 United States
AU: Neal, C
EM: cn@ceh.ac.uk
AF: Centre for Ecology and Hydrology, Maclean Building, Crowmarsh Gifford, Wallingford, OX10 8BB United Kingdom
AB: Until recently, most catchment hydrochemical studies have been based on hourly or sub-hourly measurements of water fluxes, and weekly or monthly samples of rainfall and streamflow chemistry. Trying to infer catchment hydrochemical dynamics from weekly or monthly grab samples, however, is like trying to understand a Beethoven symphony when one can only hear a single note every minute or two! New technological developments have now made it possible to monitor rainfall and streamflow chemistry at hourly or sub-hourly intervals -- similar to the timescales at which hydrometric data have long been available -- and to provide these measurements for long spans of time, not just for intensive field campaigns associated with individual storms. Here we explore how high-frequency chemical monitoring data are likely to transform catchment hydrology and biogeochemistry. We evaluate how the information content of a chemical time series depends on the sampling interval. As the sampling frequency increases, from weekly to daily to hourly, the information content of the chemical time series also increases, in some cases dramatically. However, above some sampling frequency (which varies from catchment to catchment) additional measurements will merely "connect the dots" between the existing observations, and will therefore add little additional information. We offer practical advice for estimating the frequency at which additional measurements become redundant. Experience to date shows that high-frequency chemical observations have led to important serendipitous discoveries. Continuous high-frequency monitoring of catchment hydrochemistry requires significant resources and tenacity, but what we stand to learn is well worth the effort.
DE: 1806 Chemistry of fresh water
DE: 1860 Runoff and streamflow
DE: 1871 Surface water quality
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting